I see that the Mint 14 KDE RC is out now. I currently have Mint 14 Cinnamon installed and really don't want to reinstall from scratch again. Can I just install the KDE environment from the RC through the terminal?

It isn't recommended. It's quicker to download and install Mint KDE and you get a much better system. Trying to install mint on top of cinnamonwill give you problems and you run a risk of borking them both.

"I sometimes wonder whether the world is being run by smart people who are putting us on or by embeciles who really mean it."Mark Twain

i am triple booted with mint 13 kde and did a dist-upgrade from terminal and i am currently running kde 4.9.4.i wouldnt rush into installing the 14 kde rc just yet.its better to wait for the final as the rc is still in testing.just do a upgrade from the terminal.